Air impeller construction



Aug. 17, 1965 R. B. GELBARD AIR IMPELLER CONSTRUCTION Filed Oct. 21, 1963 F'IG.|

INVENTOR.

ROBERT B. GELBARD BY m5 ATTQRMEV F'IGB United States Patent The present invention relates to an air impeller and is more particularly concerned with an improved air circulating means comprising a centrifugal blower wheel and booster vanes for increasing the pressure and flow characteristics of the blower wheel.

It is an object of the present invention to provide a one-piece molded air impeller comprising a blower wheel and integrally formed booster vanes for providing air flow characteristics normally unavailable with the usual blower wheel.

Another object of the present invention is to provide an air impeller comprising a centrifugal blower wheel component and a plurality of booster vanes so associated with the blower wheel component as to provide improved air pressures and flow characteristics without substantially increasing the noise level or losing the desirable radial diffusion capabilities of the blower wheel component.

Further objects and advantages of the present invention will become apparent from the following description and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

In accordance with what at present is considered to be a preferred embodiment of the present invention, there is provided a radial flow air impeller construction having an air inlet at the front end thereof and means for substantially closing the rear or opposite end thereof. The impeller comprises a blower wheel component including spaced front and rear rings and backward curved blades bridging the space between the rings. The front ends of the blades are connected to the rear surface of the front ring and the outer edge portions of the blades adjacent the rear ends thereof are connected to the inner surface of the rear ring. To provide a structure which can be cast or molded in one piece, a plurality of radially extending flat struts connect the hub of the impeller with the inner edges of some of the blades adjacent the rear ends thereof and at least some of these struts are provided with booster vanes formed integral with the front edges of the struts and pitched in the direction of rotation of the impeller. In order to provide optimum flow characteristics at a low noise level, these booster vanes are disposed only in the rear part of the blower wheel component.

For a more detailed description of the invention reference may be had to the following description when taken in connection with the accompanying drawing in which:

FIGURE 1 is a front View, partly in section, of the air impeller of the present invention;

FIGURE 2 is a sectional view of a portion of the impeller of FIGURE 1 taken along line 2-2 of FIGURE 1;and

FIGURE 3 is a sectional view of an air cooling device embodying the novel air impeller of the present invention.

Referring to the drawing, there is shown one embodiment of the present invention in which the blower wheel or centrifugal fan component thereof comprises an annular front ring 1 and an annular rear ring 2 which has an interior diameter at least equal to the exterior diameter of the front ring 1. .The rings 1 and 2, which are spaced from one another, support a plurality of backward curved blades 3. The blades 3 have their forward ends 4 connected to the rear surface of the front ring 1 and are joined to the inner surface 6 of the rear ring 2 along the 3,201,032 Patented Aug. 17, 1965 outer edge portions 7 adjacent the rear ends of the blade. By this construction, it will be noted that the blades 3 are disposed entirely within the area bounded by the inner surface 7 of the ring 2 and are radially coextensive with the front ring 1. j r p The impeller also includes a hub 10 for mounting the impeller on a drive shaft 11. The hub 10 is connected to some of the blades 3 by means ofthin flat struts '12 extending radially from the hub 10 to the inner edges 14 of some of the blades 3 adjacent the rear end of these blades. The struts 12 are of substantially the same thickness as the blades 3 and serve as the sole means for conmeeting the hub 10 to the blower wheel component of the impeller construction.

Integrally formed with the forward edges of the mid portions of at least some of the struts 12 are extensions 13 which are pitched in the direction of rotation of the impeller structure, adapted, as viewed in FIGURE 1, to rotate. in a clockwise direction. These extensions 13, which are in effect a continuation of the adjacent portions of struts 12, form booster vanes 15 which are disposed completely in the rear half of the impeller construction as defined by the blades 3 or in other words are rearwardly of a radial plane midway between the rings 1 and 2 both for the purpose of providing a construction having a low noise level and one which can be cast or molded from a plastic material or the like in one piece.

Air impellers of the centrifugal fan or blower wheel type, particularly those including backwardly curved blades are well known for their optimum static pressure and flow capacity characteristics combined with a low noise level as compared for example with the usual pr0- peller type fans. While it has previously been proposed to include the propeller type vanes in a centrifugal fan construction for the purpose of increasing the pressure and flow characteristics, of the centrifugal fan, in accordance with prior teachings along this line, the propeller or booster vanes have generally been positioned in the inlet or front end of the blower wheel component on the theory that by providing a greater radial flow of air through. the front or inlet end of thewheel, there would be obtained an increase in the air pressure within the centrifugal blower wheel and hence an increase in the pressure and volume of air radially leaving the wheel. However, when the propeller or booster radial vanes are positioned at the inlet end of the wheel, a substantial increase in the noise level results and the noise level of the combined structure may approach that of the straight propeller fan.

By positioning these booster vanes 15 in the rear portion of the blower component, it has been found that the vanes do not significantly increase. the noise level of the blower wheel component but do provide a substantial in crease in the pressure and air flowcharacteristics of the wheel. To obtain these improvements, it has been found that the booster vanes should include a radially extending surface, such as the leading surface 16 of struts 12 for imparting a radial movement to the air drawn into the wheel by the vanes 15 "and that the rear end of the impeller should be substantially closedeither by means of a separate plate 17 as shown in FIGURE 3 of the drawing or by means of a plate secured to the rear ring 2 of the wheel. Most of the air entering the forward or inlet end of the wheel flows through the forward end portions of the blades 3. Some of the air, in excess of that handled by an ordinary blower wheel of the same type, is scooped up by the vanes 15 so that it flows radially through the rear ends of the blades 3. In fact, tests have shown that a substantial increase in the air pressure from the configuration of the present invention results directly from the fact that the vanes 15 positioned in the rear portion of the blower wheel componentincrease the energy a m9 1 level of the air flowthrough the rear portions of the blades beyond that which is normally obtained in the absence of the vanes.

FIGURE 3 also illustrates a specific application of the impeller ofthe present invention for directing a stream of air over an evaporator 20 forming part of the cooling system for a household refrigerator. The evaporator 20 is housed in a'duct 21 having an annular opening 22 at one end thereof. The impeller of the present invention is mounted rearwardly of the opening 22 and is driven by the motor 23. The plate 17, mounted on the bracket structure 24 which supports the motor 23, substantially closes the rear end of the impeller. For the purpose of providing high impedance air seals between the impeller and the plate 17 as well as between the impeller and the walls of the ductdefining the opening22, the rings 1 and 2 are provided with outwardly extending ribs 27 and 28,which respectively extend into channels 29 and 30 to form labyrinth seals.

From'the above'description of the air impeller of the present invention, it will be seen that there has been provided a low cost impeller construction which is particularly adapted to be cast or molded in a one-piece construction; As the blades 3 and the front ring 1 are all disposed within the inner periphery of the rear blade 2 and as the vanes 15'are integral with'the struts 12, conventional molding techniques using the usual'two part mold having a parting line between the two parts of the mold along a line extendingto the forward edges 31 of the ring 2 and the blades 15 can be employed to make the impeller.

While there has been shown and described a specific embodiment of the present invention it will be understood that the invention is not limited thereto audit is intended by the appended claims to cover all modifications that fall within the true spirit and scope of the invention. V

What I claim as new'and desire to secure by Letters Patent of the United States is:

1. A radial flow air impeller construction having an' air inlet at the front end thereof, comprising a hub for mounting said impeller on a drive shaft, spaced apart front and rear annular rings concentric with said hub, the inner surface of said rear ring having a diameter at least equal to the diameter of the outer surface of said front ring,

' a plurality of blades bridging the space between said rings and having outer edge portions adjacent the rear ends thereof connected to said inner surface of said rear ring and the front ends thereof connected to the rear surface of said front ring,

a pluality of.radially extending struts connecting said hub .to the inner edges of some of said blades adjacent the rear ends thereof,

at least some of said struts including forwardly curved extensions forming with said struts, booster vanes between said hub and said blades, said booster vanes having edges spaced from said blades and being pitched in the direction of rotation of said impeller, said vanes being disposed rearwardly of a radial plane midway between said rings.

2. A radial flow air impeller construction having an air inlet at the front end thereof, comprising a hub for mounting said impeller on a drive shaft,

front and rear spaced apart annular rings concentric with said hub,

the inner surface of said rear ring having a diameter at least equal to the diameter of the outer surface of said front ring,

a plurality of backward curved blades briding the space between said rings and-having outer edge portions adjacent the rear ends thereof connected to said inner surface .of said rear ring and the'front ends thereof connected to the rear surfaces of said front ring,

a plurality of radially extending struts connecting said hub to the inner edges of some of said blades adjacent the rear ends thereof,

said struts having extensions formed integral with the front edges thereof between said hub and said blades forming booster vanes,

said booster vanes being pitchedin the direction of rotation of said impeller,

said vanes being completely disposed rearwardly of a radial plane midway between said rings,

and means for substantially closing the rear end of said impeller.

3. A plastic, one-piece radial flow air impeller construction having an air inlet at the front end thereof, comprising a hub for. mounting said impeller on a drive/shaft,

front and rear spaced apart annular rings concentric with said hub,

the inner surface of said rear ring having a diameterat' of someiof said blades adjacent the rear ends thereof,

at least some of said struts havingextensions formed integral with the, front edges thereof between said hub and said blades forming booster vanes,

said booster vanes having edges spaced from said blades and being curved in the direction of rotation of said impeller,

said vanes being completely disposed rearwardly of a radial plane midway between said rings.

References Cited by the Examiner UNITED STATES PATENTS 5/85 Dwight 230-134 9/42 Berg 103-l15 7/43 Bretzloff et al. 230-134 9/53 Meltzer et al. 230-134 9/58 Kline et al. 230-434 2,882,077 4/59 Marsh 230--134 DONLEY J. STOCKING, Primary Examiner.

HENRY F. RADUAZO, Examliner. 

1. A RADIAL FLOW AIR IMPELLER CONSTRUCTION HAVING AN AIR INLET AT THE FRONT END THEREOF, COMPRISING A HUB FOR MOUNTING SAID IMPELLER ON A DRIVE SHAFT, SPACED APART FRONT AND REAR ANNULAR RINGS CONCENTRIC WITH SAID HUB, THE INNER SURFACE OF SAID REAR RING HAVING A DIAMETER AT LEAST EQUAL TO THE DIAMETER OF THE OUTER SURFACE OF SAID FRONT RING, A PLURALITY OF BLADES BRIDGING THE SPACE BETWEEN SAID RINGS AND HAVING OUTER EDGE PORTIONS ADJACENT THE REAR ENDS THEREOF CONNECTED TO SAID INNER SURFACE OF SAID REAR RING AND THE FRONT ENDS THEREOF CONNECTED TO THE REAR SURFACE OF SAID FRONT RING, A PLURALITY OF RADIALLY EXTENDING STRUTS CONNECTING SAID HUB TO THE INNER EDGES OF SOME OF SAID BLADES ADJACENT THE REAR ENDS THEREOF, AT LEAST SOME OF SAID STRUTS INCLUDING FORWARDLY CURVED EXTENSIONS FORMING WITH SAID STRUTS, BOOSTER VANES BETWEEN SAID HUB AND SAID BLADES, SAID BOOSTER VANES HAVING EDGES SPACED FROM SAID BLADES AND BEING PITCHED IN THE DIRECTION OF ROTATION OF SAID IMPELLER, SAID VANES BEING DISPOSED REARWARDLY OF A RADIAL PLANE MIDWAY BETWEEN SAID RINGS. 